Merhaba sevgili webmaster'lar.Bir konu üzerine sizlerden yardım istiyorum.Yardım edebilecek webmaster'ları bekliyorum.

Bu aldığım hata:https://hizliresim.com/aGB7LQ

Ve buda kodları>>//session_start(); //starting session
include('z_db.php'); //connection details
$status = "OK"; //initial status
$msg="";
$username=mysqli_real_escape_string($con,$_POST['username']); //fetching details through post method
$password = mysqli_real_escape_string($con,$_POST['password']);

if ( strlen($username) < 8 ){
$msg=$msg."Username must be more than 8 char legth
";
$status= "NOTOK";}

if ( strlen($password) < 8 ){ //checking if password is greater then 8 or not
$msg=$msg."Password must be more than 8 char legth
";
$status= "NOTOK";}

if($status=="OK"){

// Retrieve username and password from database according to user's input, preventing sql injection
$query ="SELECT * FROM affiliateuser WHERE (username = '" . mysqli_real_escape_string($con,$_POST['username']) . "') AND (password = '" . mysqli_real_escape_string($con,$_POST['password']) . "') AND (active = '" . mysqli_real_escape_string($con,"1") . "') AND (level = '" . mysqli_real_escape_string($con,"1") . "')";
if ($stmt = mysqli_prepare($con, $query)) {

/* execute query */
mysqli_stmt_execute($stmt);

/* store result */
mysqli_stmt_store_result($stmt);

$num=mysqli_stmt_num_rows($stmt);

/* close statement */
mysqli_stmt_close($stmt);
}

mysqli_close($con);
// Check username and password match

if (($num) == 1) {
session_start();
// Set username session variable
$_SESSION['adminidusername'] = $username;

// Jump to secured page
print "
<script>
window.location = 'dashboard.php?page=dashboard%location=index.php';
</script>";
}else{
echo "




Username And Password Not Matched Or May Be Your Account Is Inactive.
Contact Admin For More Information.
";
}}
else {

echo "$msg
"; //printing errors

}

?>